Abstract

Recently, several real-time soft shadow algorithms have been introduced which all compute a single shadow map and use its texels to obtain
a discrete scene representation. The resulting micropatches are backprojected onto the light source and the light areas occluded by them
get accumulated to estimate overall light occlusion. This approach ignores patch overlaps, however, which can lead to objectionable
artifacts. In this paper, we propose to determine the visibility of the light source with a bit field where each bit tracks the visibility
of a sample point on the light source. This approach not only avoids overlapping-related artifacts but offers a solution to the important
occluder fusion problem. Hence, it also becomes possible to correctly incorporate information from multiple depth maps. In addition, a new
interpretation of the shadow map data is suggested which often provides superior visual results. Finally, we show how the search area for
potential occluders can be reduced substantially.